Disabling stacked scroll bars

[Carmine]

Hi,
I have a doc\view mdi app where the client frame draws both a scroll bar for itself and the tree view class contained within.
The outer frame appears immediately after the frame is created while the inner frame appears after expanding the tree items.
I've tried the PreCreateWindow and set the style to ~WS_VSCROLL with to no avail. Is there another way to disable the scroll bars ?

thanks in advance